It has become common that a digital single-lens reflex camera or a mirror-less single-lens reflex camera can record not only a still image, but also a video image. However, with regard to the sound recording quality for the sound during recording of the video image, the level of quality is yet not sufficient.
In consideration of this, some users of the digital single-lens reflex camera or the mirror-less single-lens reflex camera record the video images with the camera, and at the same time, with regard to the sound, record the sound using a dedicated sound-recording apparatus. These users later mix video image data and sound data using a personal computer or the like, and produce a video image having high image quality and high sound quality.
JP 2003-078863 A discloses a portable communication apparatus in which a video image file and a sound file are separately recorded in a memory, and, after processing such as a checking operation and a post-recording operation is executed, the video image file and the sound file are multiplexed and recorded during a storage operation.
JP 2003-199045 A discloses that, in an AV multiplexed file in which a video image signal and a first audio signal are multiplexed, the first audio signal is replaced with a second audio signal based on synchronization information.
WO 2013/108405 discloses that an embedded audio signal included in a video camera video signal is separated, and the separated digital signal is converted into an analog signal and is output.
A scheme may be considered in which a video image is captured with a camera, sound is recorded with a sound recording apparatus, the camera and a backup image recording apparatus are connected to supply the video image signal to the backup image recording apparatus, and the sound recording apparatus and the backup image recording apparatus are connected to supply the audio signal to the backup image recording apparatus. However, many of the backup image recording apparatuses, while having an HDMI (registered trademark; High-Definition Multimedia Interface) input terminal, have only an analog sound input terminal as a sound input terminal. In this case, the connection between the sound recording apparatus and the backup image recording apparatus is achieved as an analog connection, and thus, degradation of the audio signal may be caused.